VideoCaptureDeviceFactory: Change device enumeration to callback + QTKit enumerates in UI thread.

media/video/capture/file_video_capture_device_factory.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/video/capture/file_video_capture_device_factory.h"
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/strings/sys_string_conversions.h"
 #include "media/base/media_switches.h"
 #include "media/video/capture/file_video_capture_device.h"
 
 namespace media {
 
 const char kFileVideoCaptureDeviceName[] =
     "/dev/placeholder-for-file-backed-fake-capture-device";
 
 // Inspects the command line and retrieves the file path parameter.
 base::FilePath GetFilePathFromCommandLine() {
   base::FilePath command_line_file_path =
       CommandLine::ForCurrentProcess()->GetSwitchValuePath(
           switches::kUseFileForFakeVideoCapture);
   CHECK(!command_line_file_path.empty());
   return command_line_file_path;
 }
 
 scoped_ptr<VideoCaptureDevice> FileVideoCaptureDeviceFactory::Create(
-    scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
     const VideoCaptureDevice::Name& device_name) {
+  DCHECK(thread_checker_.CalledOnValidThread());
 #if defined(OS_WIN)
   return scoped_ptr<VideoCaptureDevice>(new FileVideoCaptureDevice(
       base::FilePath(base::SysUTF8ToWide(device_name.name()))));
 #else
   return scoped_ptr<VideoCaptureDevice>(new FileVideoCaptureDevice(
       base::FilePath(device_name.name())));
 #endif
 }
 
 void FileVideoCaptureDeviceFactory::GetDeviceNames(
     VideoCaptureDevice::Names* const device_names) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(device_names->empty());
   base::FilePath command_line_file_path = GetFilePathFromCommandLine();
 #if defined(OS_WIN)
   device_names->push_back(VideoCaptureDevice::Name(
       base::SysWideToUTF8(command_line_file_path.value()),
       kFileVideoCaptureDeviceName));
 #else
   device_names->push_back(VideoCaptureDevice::Name(
       command_line_file_path.value(),
       kFileVideoCaptureDeviceName));
 #endif
 }
 
 void FileVideoCaptureDeviceFactory::GetDeviceSupportedFormats(
     const VideoCaptureDevice::Name& device,
     VideoCaptureFormats* supported_formats) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   base::File file =
       FileVideoCaptureDevice::OpenFileForRead(GetFilePathFromCommandLine());
   VideoCaptureFormat capture_format;
   FileVideoCaptureDevice::ParseFileAndExtractVideoFormat(&file,
                                                          &capture_format);
   supported_formats->push_back(capture_format);
 }
 
 }  // namespace media